Robert Kubica is on course to be fit for Sunday's United States Grand Prix despite suffering concussion in his 180mph crash in Canada three days ago.

The Pole was released from hospital in Montreal on Monday after suffering only slight concussion and a sprained ankle.

BMW Sauber team boss Mario Theissen said: "It's great that he feels ready to race and is not experiencing any after-effects from the accident."

A final decision will be made after doctors have seen Kubica on Thursday.

Theissen said the team were "prepared" in case Kubica is declared unfit to drive by Formula One's chief medical officer in Indianapolis.

The team's German reserve driver Sebastian Vettel is expected to stand in.

F1 doctors will be concentrating on whether Kubica has recovered from the effects of concussion as there are potentially serious implications for drivers if they have a second heavy crash soon after a first.